Various vehicles, such as automobiles, aircraft, and maritime vessels, may include power distribution systems for generating and distributing power, often electrical, to various loads included onboard the vehicle. In the case of an aircraft, loads commonly found in the power distribution system include the flight controls, avionics, galley ovens, heaters and refrigeration units, lighting, fans, de-ice and anti-ice, etc. Typically, the power distributed to the loads by these systems is generated via an engine that is utilized both to propel the vehicle and to drive a generator. As such, the power generated by the engine must be allocated between electrical power generation and vehicle propulsion activities (and as such, the engine/propulsion mechanisms can be thought of as another load on the system, although not electrical, further dissipating energy). It is therefore desirable to design electrical power generation and distribution systems so as to distribute power efficiently between the electrical power utilization and the vehicle propulsion.
More recently, aircraft designs have increased the use of electrical power onboard an airplane. For example, recent innovations include electrical actuation (flight controls), an electrical starter-generator, which is used for engine starting and power generation, electrically powered environmental control and pressurization systems, and electrical anti-ice and de-ice systems. With the inclusion of these new loads, total electrical loading onboard an aircraft could be raised from around 100 kilowatt (kW) to around 1 megawatt (MW).
Vehicles, such as spacecraft, aircraft, missiles or the like, generally include a plurality of actuators. For example, an aircraft may include a plurality of flight control surfaces, such as along the trailing edge of a wing, and an actuator can be associated with each flight control surface in order to controllably position the flight control surface. In order to provide the motive force in order to properly position the flight control surface, an actuator may include an electrical motor. To provide the power necessary for operation of the motor, each actuator may be coupled to the power distribution system that extends through the aircraft. In instances in which the actuator is to be operative, the motor draws the necessary power from the power distribution system. In other instances, however, an actuator may be regenerative in that the actuator is able to output excess power. For example, in instances in which an actuator is moving a flight control surface to a desired position, the actuator must generally provide a braking action to stop the flight control surface at the desired position. For certain motor types, this braking action will regenerate energy by the more back electro-motive force (emf). By way of another example, in instances in which a flight control surface has been positioned out of alignment relative to the wing, such as by being lifted and therefore positioned away from the wing in order to provide localized drag, and is being moved so as to be more in alignment with the wing, such as by lowering the flight control surface, the energy transferred to the flight control surface by the airflow which pushes the flight control surface to be more in alignment with the wing may be captured by the electromagnetic forces of the motor and converted to electrical energy in the same manner as a mechanically driven actuator In this example, the actuator is essentially regenerating the initial potential energy that was used to displace the flight control surface relative to the airflow during the prior positioning of the flight control surface. In order to dissipate the regenerative power provided by an actuator, burden resistors are generally provided such that the passage of electrical current through the burden resistors will effectively dissipate the regenerative power and, in turn, will create heat. In many instances, the heat generated by the burden resistors must then be managed, e.g., rejected in a controlled manner.
As will be apparent, the dissipation of the regenerative power provided by an actuator in the form of heat is not an efficient use of the finite amount of power that an aircraft may be capable of generating during flight. This inefficiency is also manifested in terms of an increased size, rating and weight of the power distribution system necessary to deliver the requisite power, at least some of which is eventually rejected as heat. Similarly, the thermal management system must be increased in size and capacity to appropriately dissipate the heat generated in response to the regenerative power from the actuators. Additionally, the burden resistors undesirably add to the size, weight and cost of an actuator system.
Accordingly, it would be desirable to provide an improved system and method for providing power to a plurality of actuators, such as the plurality of actuators onboard an air vehicle. It would also be desirable to provide a system and method for utilizing the regenerative power provided by an actuator in a more efficient manner.